ORGANIC SPECTROSCOPY INTERNATIONAL: Production of 5-hydroxy-7-methoxy-4-methylphthalide in a culture of Penicillium crustosum

figure 3 1H NMR spectrum of 5-hydroxy-7-methoxy-4-methylphthalide (400 MHz, DMSO).

The ¹H NMR spectrum of 5-hydroxy-7-methoxy-4-methylphthalide (Figure 3) showed signals for methyl group at δ 1.95 (H-9, singlet, 3H), a signal for the methoxyl group at δ 3.79 (H-8, singlet, 3H), a signal corresponding to one methylene group at δ 5.15 (H-3, singlet, 2H), and a signal for aromatic hydrogen at δ 6.49 (H-6, singlet, 1H).

Figure 1 Structures of the compounds mycophenolic acid and 5-hydroxy-7-methoxy-4-methylphthalide.

TABLE I 1H, 13C and gHMBC NMR data for the compounds mycophenolic acid and 5-hydroxy-7methoxy-4methylphthalide

Position		Mycophenolic acid		5-hydroxy-7methoxy-4methylphthalide
Position	δ ¹³C	δ ¹H(multiplicity, J in Hz)	¹H-¹³C gHMBC*	δ ¹³C	δ ¹H(multiplicity, J in Hz)	¹H-¹³C gHMBC *
1	173.0	-		173.0	-	-
3	70.0	5.18 (2H, br s)	1; 3a	68.0	5.15 (2H, br s)	1; 3a; 4; 5; 7; 7a
3a	122.1	-	-	104.0	-	-
4	116.7	-	-	110.0	-	-
5	163.7	-	-	163.0	-	-
6	106.4	-	-	98.0	6.49 (1H, s)	1; 4; 5; 7; 7a
7	153.7	-	-	158.0	-	-
7a	144.0	-	-	151.0	-	-
8	61.0	3.74 (3H, s)	5	57.0	3.79 (3H, s)	7
9	11.5	2.13 (3H, s)	3; 3a; 4; 5	11.0	1.95 (3H, s)	3a; 4; 5
OH	-	7.67 (1H, br s)	-	-	10.59 (1H, br s)	4; 6; 5
1’	179.1	-	-	-	-	-
2’	32.7	2.38-2.47 (2H,m)	1’; 3’; 4’	-	-	-
3’	34.2	2.24-2.32 (2H,m)	1’; 2’; 4’; 5’; 7’	-	-	-
4’	133.9	-	-	-	-	-
5’	123.0	5.23-5.28 (1H,m)	3’; 7’	-	-	-
6’	22.3	3.37 (2H, br d; 6.8)	5; 7; 5’	-	-	-
7’	16.1	1.78 (3H, s)	3’; 4’; 5’		-	-

Abbreviations: s - singlet, br s - broad singlet, br d - broad doublet, m - multiplet.

Figure 2 1H NMR spectrum of mycophenolic acid (400 MHz, CDCl₃).

The ¹H NMR spectrum of the mycophenolic acid (Figure 2) showed signals for a methyl group at δ 1.78 (H-7', singlet, 3H) and a methyl group linked to aromatic ring at δ 2.13 (H-9, singlet, 3H), a signal for a methoxyl group at δ 3.74 (H-8, singlet, 3H), two signals corresponding to aliphatic methylenes in the region of δ 2.47 to δ 2.38 (H-3a' and H-3b', multiplet 2H), of δ 2.32 to δ 2.24 (H-2', multiplet, 2H), a broad doublet for a methylene group at δ 3.37 (H-6', 2H), a broad singlet at δ 5.18 (H-3, 2H) referring to an aliphatic methylene bearing oxygen, and a multiplet for a methyne group of δ 5.23 to δ 5.28 (H-5',1H).